Continuous Passive Disinfection Of Catheter Hubs Prevents Contamination And Bloodstream Infection
BACKGROUND
Central line-associated bloodstream infections (CLABSIs) are a significant cause of morbidity and mortality in hospitalized patients. The 2 predominating sources of infection are believed to be extraluminal (from the skin during and following insertion) and intraluminal (from contaminated infusates or contaminated catheter hubs). Recommendations regarding the use of chlorhexidine gluconate (CHG) for skin preparation prior to insertion and in dressings/ sponges placed at the insertion site or as part of the dressing have largely successfully addressed the extraluminal source.
Needleless connectors were developed in part to reduce the risk of needlestick injuries to health care providers. Following their introduction, there were reports of sudden increases in line-related infections. Salgado et al reported that infection rates increased following the introduction of a needleless device and that intense staff re-education on proper disinfection and use failed to improve the infection rate to the pre-needleless device baseline. Subsequently, Menyhay and Maki demonstrated in an in vitro study how a protective cap containing CHG and 70% ethanol was more successful in removing organisms from heavily inoculated catheter hubs than manual scrubbing with alcohol alone.
The aim of this study was to assess the in vivo performance of a luer access valve disinfection cap impregnated with a sponge saturated in 70% alcohol affixed to catheter hubs for preventing or reducing bacterial colonization of the intraluminal space and preventing bacterial CLABSIs.
Original and complete study article Continuous passive disinfection of catheter hubs prevents contamination and bloodstream infection.
DISCUSSION
The 5 primary causes of central catheter infections following insertion (device contamination, infusate contamination, hematogenous infection, skin organisms at the insertion site, and catheter hub contamination) have been well described and are largely agreed on. What is less well described and likely highly variable among patients as well as health care organizations is the relative extent to which each of these causes contribute to risk of infection. Assuming device and infusate contamination are relatively rare occurrences and hematogenous seeding of the external catheter tip can be prevented through limiting unnecessary device utilization by preventing infection at other sites leading to secondary bacteremia, this leaves skin organisms (extraluminal) and contaminated catheters hubs (intraluminal) as the 2 most modifiable causal pathways to preventing infection. Extraluminal sources may beline use. Timsit et al saw a 60% reduction in catheter-related infections in a randomized controlled clinical trial with the use of a chlorhexidine impregnated sponge. Based on these results, we implemented a similar protocol, with less dramatic improvement (20% reduction; authors’ unpublished data).
Preventing catheter hub contamination can take many forms. Selecting a device with the minimal necessary number of lumens decreases the likelihood of unused hubs lying in the patient’s environment to serve as a fomite and portal of entry. Resources highlighted by a recent APIC Elimination Guide championed intense “scrub-the-hub campaigns” to decrease infections in which staff are re-educated and/or incentivized to clean the hub thoroughly prior to accessing the line. These campaigns, whereas they can be successful, are analogous to hand hygiene campaigns. After bridging any knowledge deficits through education, it becomes a matter of compliance/behavior/technique, and, arguably like hand hygiene campaigns, enthusiasm and compliance are difficult to sustain over the long term without individualized and timely feedback. Even with such feedback, improvement may be difficult to sustain as demonstrated in a hand hygiene intervention described by Bittner et al. The approach of using a continuously applied alcohol impregnated sponge as a cap on the hub for a standard approach to catheter care may eliminate the problem of teaching health care providers one additional disinfection process they need to use as part of their busy patient care schedule.
The introduction of needleless connectors preceded multiple more likely to contribute to earlier onset infection, while intraluminal infections may more commonly be the source in long-term reports of outbreaks, including after a transition from split septum technology to luer activated devices, especially positive-pressure activated devices. Throughout this study, all facilities utilized a lower-risk negative-pressure luer access device.
In our study, catheter hub contamination was significantly less likely to occur, and, when it did occur, the number of recovered organisms were significantly fewer with the use of the disinfection cap. When the device was removed in phase 3, these contamination levels and numbers of organisms returned to at or near baseline levels. The most commonly recovered organism was coagulase-negative Staphylococcus species throughout the study, as expected because this skin organism is a common cause of CLABSI. The decline in CLABSI rates per 1,000 line-days did not reach statistical significance among the 3 enrolling facilities despite a 49% reduction. Statistically significant reduction is only attained after the fourth, intervention-only, facility is included. We think it is reasonable to include the data from this hospital because it is part of our health care organization and practices there are the same as at our other 3 facilities. The only reason it was not part of the formal investigation was that we did not have sufficient resources to collect samples at that site, and so we implemented the disinfection cap as a standard practice at the onset. Measurement of CLABSI was identical at this hospital as it was for the other 3 in the formal study.
The organization’s CAUTI rate was selected as the control measure for the quasi-experimental study. Similarly to the CLABSI outcome, CAUTIs are device associated; measured throughout the 4 hospitals; and adherence to fundamental infection prevention principles such as good hand hygiene, aseptic technique, and prompt removal when no longer medically necessary are apt to reduce risk of infection. There was no difference in the CAUTI rate before and after implementation of the disinfection cap. However, when the device was removed from use during, the CAUTI rate decreased significantly, suggesting that any change in the CLABSI rate was more likely impacted by removal of the intervention (because CAUTI and CLABSI rates went in opposite directions) rather than any changes to patient population or basic infection prevention initiatives. A visual depiction of the relationship between CLABSI attack rate, CLABSI per device-day rate, contamination, and CAUTI per 1,000 patient-days rate is in Figure 1.
We evaluated a novel alcohol impregnated disinfecting cap that, once applied to the hub, remains in place until it is accessed. Its properties are likely both chemical (alcohol) and physical (cap remains in place and protects against external contamination). Oto et al observed a similar marked reduction in contamination rates in a randomized controlled clinical trial of a protective hub cap (without any disinfectant) used in a critical care unit.20 An earlier study by Menyhay and Maki evaluated a similarly designed device with a CHG and 70% alcohol impregnated sponge within a threaded cap. Their in vitro study demonstrated that the cap design and disinfectant combination were more effective in eliminating bacterial contamination than the conventional scrub technique using an alcohol pad. That study did not determine whether the higher performance was due to disinfectants used or the cap design. The disinfection cap evaluated in this study does not contain CHG, but the evaluation was in human subjects in actual hospital practice rather than a controlled laboratory environment. Two recent studies have described similar effects of an alcohol based disinfection cap in preventing CLABSIs. Pong et al reported a reduction from 0.93 to 0.30 per 1,000 line-days over the course of 12 months in a single neonatal intensive care unit. Similarly, Sweet et al reported a reduction from 2.9 to 0.4 per 1,000 line-days in an inpatient oncology unit. Both studies achieve a lower overall rate than our experience following their intervention, yet neither study described using a control group, and both are restricted to single units, whereas our investigation reports comprehensive data from a 4-hospital health care system. Sweet et al include a business analysis utilizing a cost per CLABSI of $30,000, which is within the range of published estimates. However, a recent study by Barnett et al suggests that the attributable length of stay because of CLABSI (arguably the primary driver of such costs) is much less than previously reported. If our study applied the same methodology with the estimated cost of $30,000, the 1-year annualized savings would be $390,617. In our own analysis, we described the cost per catheterized patient-day ($2.07), the infections and deaths avoided (21 and 4, respectively), and the hospital’s ability to increase admissions (13) in a single year. Whether this translates to profit for an organization is debatable, but our analysis allows for this debate to be framed from societal and payer perspectives in addition to the more traditional hospital-based expenditure-profit point of view.
This study has limitations. The outcome, in the form of CLABSI, is a surveillance-based definition and, as such, likely overestimates the occurrence of clinical disease. It is, however, a standardized definition for NHSN reporting and is the measure for recent changes to the Centers for Medicare and Medicaid Services inpatient prospective payment system. There has been a recent report of inconsistent application by IP of these same NHSN-based definitions. However, the individuals detecting and determining CLABSIs for this study took the first 2 CLABSI-based NHSN case studies with a 100% success rate in applying the definitions compared with 73% correct response rate nationally. Compliance with using the disinfection cap required frequent reinforcement from IPs, research nurses, and vascular access team nurses.
However, any lack of compliance in using the disinfection cap would bias the findings of this study toward the null hypothesis of no effect. The average length of stay for the cost analysis is markedly lower than other published estimates, but, again, these conservative estimates would bias the findings toward the null, cost-prohibitive hypothesis. The inclusion in the results of findings from the fourth, intervention only, hospital (hospital D) might be debatable. Although no patients were enrolled for the study at hospital D, CLABSI surveillance is uniform for both numerator and denominator collection across the health care system. Similarly, all infection prevention-oriented policies, procedures, and performance improvement initiatives are uniform throughout the system. The baseline period for hospital D does not include any additional interventions and is limited to 5 months to avoid overlap with the introduction of the chlorhexidine impregnated sponge that was implemented across the system in August 2009. Recognizing that its inclusion may be controversial, we presented the results including and excluding hospital D.
This study demonstrated the effectiveness of an alcohol impregnated cap for catheter hubs in preventing intraluminal contamination and infection. With the use of such a device, contamination was significantly less frequent and, when it did occur, involved fewer organisms. Infection rates also declined, and both contamination and infection rates returned to near baseline levels after the device was removed from use. During the intervention, another device-associated infection rate in the form of CAUTI remained unchanged and actually declined significantly when the intervention was discontinued and CLABSI rates returned (increased) to their baseline. The use of this device is estimated to be financially attainable for the organization after accounting for the reduction in infections, attributable length of stay, deaths, and the cost of the device. At the conclusion of this investigation, our Infection Control Committee approved the permanent introduction of this device for use with central lines, and it is now the standard of practice for the organization.
